Protective device.



W. W. DEAN.

PROTECTIVE DEVICE.

APPLICATION FILED MAY 19, 1905.

Patented Jan. 19, 1915.

`pose of protecting the' outside lines, or the UNITED sTATEs PATENT ormoni.

l`WI|LIAMI W. DEAN, 0F ELYRIA, OHIO; CURTIS B. CAMP, TRUSTEE, APPINTED BY COURT.

Specication of Letters Patent.

PROTECTIVE DEVICE.

Patented Jan. 19,1915.

To all whom it may concern Be it known that I, VILLIAM IV. DEAN, acitizen of the United States, residing at Elyria, in the county of Lorain and State of Ohio, have invented certain new and useful Improvements in Protective Deviees,`of which the following isa specification, reference being had therein to vthe accompanying drawing.

My invention relates to protective devices i for electrical apparatus and circuits, and particularly to sneak current arresters, or so-called heat coils as used in telephone systems. ployed in telephone exchanges, for the purinside apparatus connected therewith, from the eiieets of such currentsas would fail Vtovbe excluded by high potential arresters or spark gaps. Ordinarily, one of the socalled heat coils is includedin each side of .each line,` and all thesedevices'are mounted together on a convenient frame or rackwith terminals such as to ail'ord easy means of connection, and for testing. In mounting the devices, the frame or rack commonly has on'each strip rows of contact springs in and between which the individual heat coils aremounted, there being one group in the row for each line there represented, and two heat coils, one for each side of the line.

Such an arrangement is shown in the patent to Williams, No. 588,206, granted Aug. 17, 1897. A ground strip is provided. which is sometimes connected to the frame itself, andv when a coil becomes'hot owing to excessive current, it heats up and melts a body of solder and thereby releasesa normally held.

plify and cheapen the protective outfits now in use, and at the same time increase the -eiicienciT of the apparatus. Instead of using a coil for eachside of the line, I propose to use 455 a single device forboth sides of the line,

, circuit.

Such devices are commonly em which may comprise an aggregation of either coils or other agencies for developing heat or for otherwise controlling the line In its simplest form my invention comprises a coil composed of two windings differentially laid upon a spool arranged in proximity to a soldered surface by which 1s supported a spring or pair of springs controlling the line and switch-board circuits. The line is led in and one side goes through each of the' vdifferential windings. Voice currentsare .thus unaffected, since they neutralize each other in the coils. Sneak currents, however, produce a double effect, since both coils act upona single mass of solder.

The economy and simplicity of my device will be seen at a glance without explanation, only one Coil being required perline instead of two.

understood that theinvention is independent thereot` in its essential principle, being usable with any svsteln.

Instead of coils'I also contemplate providing two pieces of carbon. or the like, for heating means, in proximity to the same solder or other circuit controlling device.

My invention is illustrated in the'accompanving drawing, wherein- Figure 1l shows a heat coil embodving the invention. and coperating parts and connections; Fig. 2 is a modification of the heat coil; 3 is a modification of theentire device and Fig. 4, is held detail view of the plug and detaining plate.

,In the drawings. Fig. 1, A is a heat coil, supported in any suitable manner. comprising the spool. a (which mav be of copper), wigth two differential windingso and a2.- This coil has. a plug'of metal. B. lhaving a in the spool in a position to be heated by means ol" the windings. The-plug is of a metal such as copper, which will conduct heat rapidly, and the head, l), therefore receives the generated heat from the stem. Upon this head'is soldered one end of a detaining strip, D, of metal, having hushed openings, d and d', receivingr the vends of the line springs, e, and e', of the line set, E,

. for sneak currents.

corresponding to the set shown in Fig. 1 of the Williams patent referred to. Each spring'has a normally open ground contact, g or g', and each may have a normally closedcontact connected to the switchboard. circuit 5--6; but in the simpler form shown the line is n ot opened but merely grounded Circuitjs tracedfrom line wire 1 to spring,'e, wire 3, windin'ga,V

wire 5, the switchboard apparatus, wire 6, windlng af-,wire 4,spr1ng ve, w1re 2 and out.

The operation'is of course obvious without description; When the coil heats the solder,

C, melts (or the equivalent cement. softens). The sp'ring's, e, e', drop to ground contacts.,

Contact springsjmounted upon an iron base w which is connected to ground. The .con-

tact springs e ande are mounted4 on and insulated from the baseby insulating strips,

F, held to the base byscrewsf Allarm, G

extends horizontally vfrom where it is se- 'cured tothe base by the screws, f,'ove r the contact springs e and' e,to a point approximately midway the length of the springs e and e where it -isbent upward to form a support for the spool a of the `heat coil A. This coil isconstructed substantially the same as that shown in Fig. 1 and is provided with a headed copper plug B, which is different from that' shown in Fig. 1 in that it 'is provided with a button. B3 adaptedto'engage a slotd2 formed in the detaining strip D. The strip D shown inthis figure 1s provided with a bushed opening d3 at each end, and theplugB is adapted to turn in the spoola.'

When the device is in operative position as shown in Fig. '3, the spring e has'its hooked end e -engaging thel lower hushedopening d3 and the lower end of the slot d2 is in contact with thev button B3. The detaining strip ris soldered to the head bA of the plug B and preferably also to the button B3. The spring c is normallyheld from ,contact with the ground plate and the spring e normally pulls downward on the detainingV plate D. When the coil heatsand thesolder melts the contact spring c pulls the plate down sov as to allow it to engage araised contact e2 and to force the spring e into engagement with'a contact e", thus groundingv both sides of the line. vAs the coils {1ool,the detaining plate becomes resoldered in this depressed position. It is then only necessary to remove the plug and reverse it,`whe i1` the device is again in Aoperative condition. Y

' I wish it distinctly understood that 'I' am not. confined to the specific embodiment of my invention herein disclosed, butthat 'the adapted toi respond to. an electric .current connected ,l in diiferentp'ortions of said line circuit' and vseparately;or jointly acting to operate-'saidj'switch and means for grounding' the switch when operatedV 2. In a protective device for velectrical systems, the.combination with a line circuit, of aV controlling switch therefor, a plurality of heating devices to jointly or separately operate said switch, and aground plate contacting' with said switch when the switch-is operated.

In a protective device fory electrical systems, the combination with a line circuit, of a controlling switch therefor, a plurality of heat coilsconnected in different portions of said circuit to jointly or separately actI upon said switch to operate the saine, and means for grounding the switch. v

' 4. In aprotective device for electrical systems, the combination of a thermally operable switch, said switch having alurality -of current' ground contact, 'and controlled devices to jointly or separately act to put the switch en the ground con-v .I `-to engage with the ground contact.

16. In a protective device fory electrical systems, the combinationwith a` switch, of thermally operable securing means therefor, 't-plurality `of current controlled de vices, and means whereby suchv devices are yadapted'toa-ct singly or jointly lto release said securing means.

. 7. Inl a protectivev device for' electrical v systems, lthe combination withl av switch, of thermally operablesecuringfmeanstherefor,

and a plurality Yurre'nt v controlled devicesv adapted to fac ""fsingly' or jointly to release's'aid securin means, said means having provision, foi 'automatically' resecuring' itself infcondition adapted for another peration when sliich` switch is manually res adjusted. 4 I

18. Iii-"an 'electrical syste`1i1, a circuit to be protected'and `c 'ntrolling means for said circuit comprisngcntacts connected thereto, Ia mechanical sip'port fo'r said contacts,

a ,l'ioldi'ng devic'e I i the' contacts secured on the support by fusible material, and a pair of heating elements mounted in proxiinity to said `fusible material and connected in opposite sides of thecircuit7 substantially as described. j

9. In an electrical system, a circuit to be protected, a protective device comprising controlling' contacts, and a self-s0lderiiig heat cartridge mounted on the support and con-trolling tlie'contacts, said cartridge liaring two windings and said windings being co inected in different parts of the circuit to be protected, whereby sneak currentsin -eitlier one or both of said difeiient p'arts of the circuit will actuate the protective device, substantiall)v as described.

l0. In airelectrieal system, a circuit to be protected, controlling contacts for said circuit, a mechanical support for said contacts, and a self-soldering' heat cartridge controllingsaid contacts, said cartridge haviiig tiro windings and said windings being Si. Har) connected in opposite sides of the circuit to be protected, substantially as described.

l1. ln an electrical sys-teni, circuit to be protected and a protective devicey constituting a single current controlled element, with means to control both sides ot the circuit, and a. plurality of actuating means therefor connected and responsive to current in ArD. T. Liner, M. E. MizrR. 

